Delivery unit

ABSTRACT

Delivery units are already known which have a drive rotor and an output rotor driven by the drive rotor, which are supported in a housing, interact in a meshing manner through a spur toothing in each case and draw fluid through at least one inlet and push said fluid out through an outlet, wherein the inlet and the outlet are separated from each other by two separating webs. In order to control the flow rate through the delivery unit, a rotational speed control, a bypass control, or, for gases, a suction throttling, for example, can be carried out. A rotational speed control is energy efficient, but very expensive, because an electric motor must be used, the rotational speed of which can be controlled. In the bypass control, the fluid is delivered from the outlet through a bypass back to the inlet, which however is energetically unfavorable and connected to hydraulic losses. The delivery unit according to the invention is improved in such a way that on the inlet side the flow rate can be controlled very easily and with few hydraulic losses and on the outlet side the inner compression can be adjusted in the event of delivery of gases. According to the invention, at least one of the separating webs ( 9,10 ) has at least one control opening ( 12 ), the opening cross-section of which can be controlled with a control slide ( 13 ).

BACKGROUND OF THE INVENTION

The invention relates to a delivery unit. A delivery unit is known already from DE 10 2004 026 048 A1 comprising a drive rotor and an output rotor driven by the drive rotor which are mounted in a housing, interact in a meshing manner via a respective spur toothing and draw fluid through at least one inlet and push said fluid out through an outlet, wherein the inlet and the outlet are separated from each other by two separating webs. In order to control the flow rate through the delivery unit, a rotational speed control, a bypass control or, for gases, a suction throttling can, for example, be carried out. A rotational speed control is energy-efficient but very expensive as an electric motor must be used, the rotational speed of which can be controlled. In the case of bypass control, the fluid is delivered from the outlet via a bypass back to the inlet, which however is unfavorable in energy terms and is associated with hydraulic losses.

SUMMARY OF THE INVENTION

In contrast, the delivery unit according to the invention has the advantage that on the inlet side the flow rate can be controlled very easily and with few hydraulic losses and on the outlet side the inner compression can be controlled in the event of the delivery of gases, by virtue of the fact that at least one of the separating webs has at least one control opening, the opening cross section of which can be controlled by a control slide. The design according to the invention, in contrast to the prior art, requires less space for the volume flow control, is more cost-effective and is more energy-efficient.

Working chambers with a volume that increases in the region of the inlet in the direction of rotation and decreases in the region of the outlet in the direction of rotation are formed between the spur toothings of the rotors, the maximum volume of the working chambers being formed at a first transition point in the region of a first separating web and the minimum volume being formed at a second transition point in the region of a second separating web.

According to a first embodiment, at least one control opening connected to the inlet side is arranged in a region of the first separating web which lies behind the first transition point in the direction of rotation, as the respective working chambers are in this way variably fluidly connected to the inlet via the point of their maximum volume. When the volume of the working chambers starts to decrease and the latter are still fluidly connected to the inlet via the control opening, part of the fluid drawn out of the working chambers is pushed back again into the inlet. The amount delivered per revolution thus decreases.

According to a second embodiment, at least one control opening connected to the outlet side is arranged in a region of the first separating web which lies behind the first transition point in the direction of rotation, as in this way the inner sealing of the delivery unit can be controlled.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is shown in a simplified fashion in the drawing and explained in the following description in more detail. In the drawing:

FIG. 1 shows in section a delivery unit to which the invention could be applied,

FIG. 2 shows a sectional view of a rotor housing according to the invention according to FIG. 1 in a first exemplary embodiment,

FIG. 3 shows a three-dimensional view of the rotor housing according to FIG. 1 and FIG. 2, and

FIG. 4 shows a sectional view of a rotor housing according to the invention according to FIG. 1 in a second exemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 shows in section a delivery unit to which the invention could be applied.

The delivery unit 1 has a drive rotor 2 and an output rotor 3 driven by the drive rotor 2 which are both mounted in a rotor housing 4. The drive rotor 2 is driven by a motor 5, for example an electric motor, via a driveshaft. The two rotors 2, 3 each have a spur toothing 6, for example a cycloidal spur toothing, which interact with each other in a meshing manner and draw fluid in through at least one inlet 7 in the rotor housing 4 and push said liquid out through an outlet 8 in the rotor housing 4 following the positive displacement principle. Working chambers 14 are formed between the spur toothings 6 of the rotors 2, 3. The axes of rotation of the two rotors 2, 3 extend obliquely to each other and thus enclose an angle other than 180 degrees so that the volume of the working chambers 14 alternately increases and decreases during a revolution of the drive rotor 2. At the inlet 7 the volume of the chambers 14 increases in the direction of rotation and decreases at the outlet 8 in the direction of rotation so that fluid is drawn into the working chambers 14 at the inlet and is pushed out of the working chambers 14 at the outlet. The rotor housing 4 is enclosed by a pump housing 15. The inlet 7 and the outlet 8 of the rotor housing 4 are sealed relative to each other inside the pump housing 15, for example by means of separating walls 16, 17 or other sealing means. The separating walls 16, 17 lie, for example, in the region of the separating webs 9, 10.

To deliver liquids, the working chambers 14 must be fluidly connected either to the inlet 7 or to the outlet 8 so that no closed chambers 14 are created in which the incompressible liquid is compressed by a reduction in the volume of the chambers 14 and an unacceptably high elevated pressure occurs which could damage the delivery unit. In the prior art, the rotors 2, 3 are also mounted in such a way that in the event of a predetermined elevated pressure they are pressed apart from each other in such a way that the elevated pressure is relieved by a short circuit with the adjacent working chambers. Closed working chambers 14 are acceptable for the delivery of gases as gases are compressible and a so-called inner compression is desired inside the closed chambers 14.

FIG. 2 shows a sectional view of the rotor housing according to the invention according to FIG. 1 in a first exemplary embodiment. In the view according to FIG. 2, parts which are identical or function in an identical fashion to those in the view according to FIG. 1 have the same reference numerals.

The inlet 7 and the outlet 8 are separated from each other in the circumferential direction of the rotor housing 4 by two separating webs 9, 10.

According to the invention, it is provided that at least one of the separating webs 9, 10 has at least one control opening 12, the opening cross section of which can be modified by a movably mounted control slide 13. A plurality of control openings 12 are, for example, arranged behind one another in the direction of rotation of the rotors 2, 3. The control opening 12 is, for example, a slot-shaped through-opening. The control slide 13 can, for example, be adjusted electrically, pneumatically or hydraulically and interacts with the at least one control opening 12 to open or close it. A control opening 12 that is not completely covered by the control slide 13 is fluidly connected to the inlet 7 or the outlet 8 and opens into one of the working chambers 14 depending on the position of the rotors. The control slide 13 can be adjusted in or counter to the direction of rotation of the rotors 2, 3 and/or axially with respect to one of the axes of rotation.

The maximum volume of the working chambers 14 is formed at a first transition point A in the region of the first separating web 9 and the minimum volume is formed at a second transition point B in the region of the second separating web 10. The separating webs 9, 10 cover a predetermined angular range around the transition points A, B. Viewed in the direction of rotation, the volume of the chambers 14 decreases from the first transition point A to the second transition point B and increases from the second transition point B to the first transition point A.

According to the first exemplary embodiment, the at least one control opening 12 is arranged on the first separating web 9, in front of the separating wall 16, viewed in the direction of rotation of the rotors 2, 3, in such a way that it is fluidly connected in the open state to the inlet 7. Moreover, the at least one control opening 12 is, for example, arranged in such a way that it lies in a region of the first separating web 9 which lies behind the first transition point A in the direction of rotation. In this way, depending on the position of the control slide 13, the respective working chambers 14 can be connected to the inlet 7 variably via the control opening 12 over the first transition point A, so that by reducing the volume of the respective working chamber 14 a part of the fluid drawn out of the working chamber 14 is pushed back again into the inlet 7. Because of the “late” closing of the inlet 7, the amount delivered per revolution decreases, effecting a simple and energy-efficient volume flow control on the inlet side.

For the delivery of gases, the at least one control opening 12 can alternatively also be designed on the first separating web 9, in front of the first transition point A in the direction of rotation of the rotors 2, 3. In this alternative embodiment, the volume flow control is effected by the “early” closing of the working chambers 14 at the inlet 7, as a result of which the working chambers 14 are not completely filled and the hydraulic throttle losses are reduced in comparison to the “late” closing of the inlet 7. Of course, for this case one or more control openings 12 can also be provided in front of the first transition point A, and one or more control openings 12 behind the first transition point A in the direction of rotation.

FIG. 3 shows a three-dimensional view of the rotor housing according to FIG. 1 and FIG. 2. In the view according to FIG. 3, parts which are identical or function in an identical fashion to those in the view according to FIG. 1 and FIG. 2 have the same reference numerals.

FIG. 4 shows a sectional view of the rotor housing according to the invention according to FIG. 1 in a second exemplary embodiment. In the view according to FIG. 4, parts which are identical or function in an identical fashion to those in the view according to FIG. 1 to FIG. 3 have the same reference numerals.

According to the second exemplary embodiment, the at least one control opening 12 is also arranged on the first separating web 9, but it is fluidly connected in the open state to the outlet 8 by being designed on the first separating web 9 behind the separating wall 16, viewed in the direction of rotation. In the second embodiment, it is not the volume flow but the inner sealing that is controlled by means of the control openings 12 and optimal operation of the delivery unit in terms of energy is thereby achieved. Because of the inner sealing, the second embodiment is suited only for the delivery of gases. 

1. A delivery unit comprising a drive rotor and an output rotor driven by the drive rotor, in which the rotors are mounted in a rotor housing, interact in a meshing manner via a respective spur toothing and draw fluid through at least one inlet and push said fluid out through an outlet, wherein the inlet and the outlet are separated from each other by two separating webs, characterized in that at least one of the separating webs (9, 10) has at least one control opening (12), an opening cross section of which can be controlled by a control slide (13).
 2. The delivery unit as claimed in claim 1, characterized in that working chambers (14), each with a volume that increases at the inlet (7) in the direction of rotation and decreases at the outlet (8) in the direction of rotation, are formed between the spur toothings (6) of the rotors (2, 3), a maximum volume of the working chambers (14) being formed at a first transition point (A) in a region of a first one of the separating webs (9) and the minimum volume being formed at a second transition point (B) in a region of a second one of the separating webs (10).
 3. The delivery unit as claimed in claim 2, characterized in that at least one control opening (12) is arranged in a region of the first separating web (9) which lies at least one of in front of and behind the first transition point (A), viewed in the direction of rotation of the rotors (2, 3).
 4. The delivery unit as claimed in claim 1, characterized in that the control slide (13) can be adjusted one of electrically, pneumatically and hydraulically.
 5. The delivery unit as claimed in claim 1, characterized in that the control slide (13) can be adjusted in the direction of rotation of the rotors (2, 3).
 6. The delivery unit as claimed in claim 1, characterized in that the control slide (13) can be adjusted counter to the direction of rotation of the rotors (2, 3). 